Restructure modules with per-module addon subdirs

- Each module (outline, interact, screenshot) now has its own addon/
  subdir with .toc, .lua, and Bindings.xml
- Core WeirdUtils addon lives in src/core/addon/
- build.zig supports compile-time feature gating via -D options
- main.zig uses build_options for conditional imports and addon embedding
- Module addons only load when their module is compiled in
- 'zig build all-variants' produces full.dll + 3 single-module DLLs

src/interact/addon/Bindings.xml

@@ -0,0 +1,11 @@
+<Bindings>
+    <Binding name="Interact" header="INTERACT">
+        InteractNearest(0)
+    </Binding>
+    <Binding name="Interact (auto-loot)">
+        InteractNearest(1)
+    </Binding>
+    <Binding name="Loot All Corpses">
+        LootAllCorpses()
+    </Binding>
+</Bindings>

src/interact/addon/Interact.lua

@@ -0,0 +1,31 @@
+-- Interact addon (embedded in DLL, loaded from memory)
+-- Part of WeirdUtils - only loaded when interact module is compiled
+
+INTERACT_VERSION = 1
+
+BINDING_HEADER_INTERACT = "Interact"
+
+local frame = CreateFrame("Frame")
+frame:RegisterEvent("ADDON_LOADED")
+frame:RegisterEvent("PLAYER_LOGIN")
+
+frame:SetScript("OnEvent", function()
+    if event == "PLAYER_LOGIN" then
+        DEFAULT_CHAT_FRAME:AddMessage("|cff00ff00Interact|r v" .. INTERACT_VERSION .. " loaded")
+    end
+end)
+
+SLASH_INTERACT1 = "/interact"
+SlashCmdList["INTERACT"] = function(msg)
+    msg = string.lower(msg or "")
+    if msg == "" or msg == "help" then
+        DEFAULT_CHAT_FRAME:AddMessage("|cff00ff00Interact|r commands:")
+        DEFAULT_CHAT_FRAME:AddMessage("  /interact - Show this help")
+        DEFAULT_CHAT_FRAME:AddMessage("  Key bind: Interact - Interact with nearest NPC/object")
+        DEFAULT_CHAT_FRAME:AddMessage("  Key bind: Interact (auto-loot) - Interact and auto-loot")
+        DEFAULT_CHAT_FRAME:AddMessage("  Key bind: Loot All Corpses - Loot all nearby corpses")
+        DEFAULT_CHAT_FRAME:AddMessage("  /run InteractNearest(0) - Interact without loot")
+        DEFAULT_CHAT_FRAME:AddMessage("  /run InteractNearest(1) - Interact with auto-loot")
+        DEFAULT_CHAT_FRAME:AddMessage("  /run LootAllCorpses() - Loot all nearby corpses")
+    end
+end

src/interact/addon/Interact.toc

@@ -0,0 +1,8 @@
+## Interface: 11200
+## Title: Interact
+## Notes: Nearest NPC/object interaction and bulk looting
+## Version: 1.0
+## Dependencies: WeirdUtils
+
+Interact.lua
+Bindings.xml